Non-suicidal self-injury (NSSI), deliberate harm to the body without suicidal intent, is highly prevalent in young adults, with 1 in 10 college students engaging in over 100 episodes in their lifetimes. Consequences of NSSI are severe, including physical injury ranging in medical severity, distress from shame associated with the behavior, social isolation, psychological symptoms, and increased risk and lethality of NSSI over time, resulting in more severe injuries, suicide attempts, and even death. Despite the prevalence and significant consequences of the behavior, no empirically supported treatments specific to NSSI exist. The purpose of the research plan included in this K23 Career Development Award is to develop, implement, and evaluate an intervention specifically for NSSI in young adults, the Treatment for Self- Injurious Behaviors (T-SIB). This time-limited intervention will integrate theoretically-based strategies whose utility has been identified through empirical research, including a functional analysis of NSSI, motivational interviewing techniques, and individualized behavior therapy with the goal of reducing frequency and severity of NSSI. The research plan consists of 2 phases. During Phase 1, I will develop a comprehensive treatment manual and therapist training program for T-SIB and treat 12 patients in an open pilot trial. After further refinement of the intervention, Phase 2 will involve the treatment of 60 patients in a randomized controlled pilot study to determine the feasibility and acceptability of T-SIB, investigate change in NSSI frequency and severity between T-SIB and treatment as usual (TAU) through a 3-month follow up period, and evaluate the research design of the randomized controlled pilot study to inform both the utility and design of a larger randomized clinical trial, to be proposed as an R01 in Year 5 of the award. The training plan proposed in this application will allow me the opportunity to develop and refine the skills necessary to continue my career as a clinical scientist working with self-harming individuals. Through formal training, the proposed research plan, mentorship experiences with Drs. Miller and Spirito, and regular meetings with my consultants, all leaders in their fields, I will be able to fulfill the following training goals: 1) to gain experience in treatment development, design, and outcome studies, including the methodology and analysis of clinical trials;2) to increase expertise in and knowledge of the phenomenology and treatment of NSSI specifically and self-harm in general in young adults;3) to advance my education in the ethics of clinical research trials and diversity training;4) to increase my experience in grant writing and manuscript preparation;and 5) to gain further clinical training and supervision in motivational interviewing and the treatment of self-harming individuals. This K23 Award will advance my training and is the logical next step in preparing me for a career as an independent clinical researcher specializing in self-harm behaviors.